The VPR sounder is available in two popular formats - VPR-SA2 and VPR-SA4 The VPR-SA2 sounder is designed for applications where low current consumption relative to sound output is required, with a 103 dBa output requiring only 11mA at 24Vdc. The VPR-SA4 sounder is designed for applications requiring maximum sound output, and offers the best sound output to cost of any sounder currently on the market.

With an operating frequency of 800Hz - 1000Hz, each sounder provides sound within the frequency range specified by BS 5839. Each sounder also has a wide operating voltage of 8 - 35Vdc. Tones are available by selecting warble, sweep or pips via the jumper fitted to the PCB. By using three wires, a second stage alarm may be switched so that the continuous tone will override the tone selected.